The field of the disclosure relates generally to centrifugal pump assemblies, and more specifically, to centrifugal pump assemblies that include an axial flux electric motor coupled to an impeller.
At least some known centrifugal pumps include an impeller for channeling a fluid through the pump. The impeller is coupled to a shaft that is also coupled to a rotor of an electric motor such that rotation of the rotor causes rotation of the impeller. In at least some known electric motors, the rotor is spaced from a stator such that there is an ever present axial force of attraction in a first direction between the magnets on the rotor and the steel core of the stator. Additionally, the rotating impeller imparts kinetic energy into the pumped fluid as it spins, which increases the pressure of the fluid. There is a resulting axial suction force in an opposite direction acting on the impeller as this pressure increases. In at least some known centrifugal pumps, when operating at high speeds, the axial suction force is larger than the axial magnetic force and may pull the rotor away from the stator, thus causing interruptions in the operation of the electric motor.
Additionally, in at least some known pumps, the axial magnetic force may cause the rotor to contact the stator when the pump is non-operational, and also for a short duration after rotation initialization but before the impeller draws the rotor away from the stator. During low speed rotation, the rotor and stator may contact each other and cause large friction forces between the two components. Such friction forces may shorten the service lifetime of the electric motor and may also generate undesirable noise.